added Hashrate to consensus.Engine interface

consensus/consensus.go

@@ -113,6 +113,10 @@ type Engine interface {
 	// consensus rules that happen at finalization (e.g. block rewards).
 	FinalizeAndAssemble(chain ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, etxs []*types.Transaction, manifest types.BlockManifest, receipts []*types.Receipt) (*types.Block, error)
 
+	// Hashrate returns the measured rate of the search invocations
+	// per second over the last minute.
+	Hashrate() float64
+
 	// Seal generates a new sealing request for the given input block and pushes
 	// the result into the given channel.
 	//